News Release

Research aims to arm plants with natural pesticide

A University of Guelph professor is working to develop genetically modified plants that can ward off insects and other pests naturally.

Plant physiologist and biochemist Barry Shelp, and longtime research colleague Alan Bown of Brock University, hope the research will save crops and money for farmers and reduce the need to pump chemicals on to fields.

They are studying a non-protein amino acid called gamma aminobutyric acid (GABA), which is involved in nerve transmission in animals. Although scientists are uncertain about its function in plants, they know that the substance accumulates rapidly in plants in response to stresses such as temperature shock, nitrogen deficiency and wounding by insects. For example, an insect can cause the plant to boost its production of the compound simply by chewing a stem or root or even by tiptoeing across a leaf.

Shelp hopes to engineer crop plants so that they produce more of this naturally-occurring pesticide on a regular basis. The result would be pests such as nematodes or insects ingesting GABA, which, in turn, would interfere with their nerve function and development. The substance would not be produced in sufficient amounts to harm animals or humans. “This could provide another tool for managing invertebrate pests,” Shelp said. “It seems particularly promising because it should be effective against a wide range of pests and because resistance is unlikely to evolve.”

The researchers have already engineered tobacco plants with GABA levels several times higher than in non-transgenic plants and with the desired resistance to a model pest, the root-knot nematode. The results also showed that the genetically modified plants deterred leaf feeding by the tobacco budworm. Nematodes, including the root knot nematode — a microscopic worm that feeds on roots of plants such as tomatoes — cause damage to the tune of $100 billion U.S. in field and vegetable crops each year. Insects cause about $70 billion worth of damage annually.

Shelp and Brown have applied for a patent on the technology and discussed its use in economically important crop species with biotechnology and seed companies. Shelp stresses that it would take at least three to five years before newly engineered plants would be ready for testing. He is also studying other applications for his research. For example, it might be possible to engineer plants with improved tolerance to temperature shock or better use of nitrogen, reducing economic and environmental costs of chemical fertilizers.

Shelp began this project through a more fundamental interest in how carbon and nitrogen interact in plants. “My philosophy has always been that while we’re doing these things, we should be looking for applications.”